For this function determine whether y varies directly with x

For this function, determine whether y varies directly with x. If so, find the constant of variation and write the function rule. 1. x: -2, 1, 2 y: 3, 4, 7

Solution

x = -2 ; y = 3

x =1 ; y = 4 -----> slope between the two points = ( 4 -3)/( 1 +2) = 1/3

x = 2 ; y = 7-----> slope between the two points = ( 7 -4)/( 2-1) = 3

slope is not constant

So, y does not varies directly with x